Civil Engineering MCQAE Level Civil Engineering
Lacey formula for scour depth (R) at a bridge/weir site in alluvial soil in terms of design discharge per unit width q and silt factor f is:
Irrigation EngineeringScour Depth LaceyMEDIUM
Choose the correct answer
A
R = 1.35 (q^2/f)^(1/3)
B
R = 0.47 (Q/f)^(1/3)
C
R = q / (0.47 f)
D
R = 4.75 sqrt(q/f)
Correct Answer
A. R = 1.35 (q^2/f)^(1/3)
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Lacey scour depth: R = 1.35 (q^2/f)^(1/3), where q = discharge per unit width (cumec/m), f = Lacey silt factor. Used at bridge and weir sites to determine the maximum depth of scour below HFL for safe foundation depth.
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